Acoustical considerations in designing musical auditoriums are complex with many interrelated factors. An ideal reverberation time (RT) must balance fullness of tone with loudness, definition, and diffusion. However, RT alone does not guarantee acoustic excellence - it is one contributing factor. Definition is satisfactory if the initial time delay gap is under 20 milliseconds, direct sound is loud relative to reverberant sound, and there is no echo. Providing adequate bass over large audiences is difficult since many instruments are weak in fundamentals.

1. Acoustical considerations in the Architectural Design of Musical Auditoriums Presented by Ar.Jaikumar Ranganathan Lecturer Dept of Architecture,HCE Chennai,India

2. Acoustical considerations Since no music hall is built for one specific type or style of music, the RT must be a meticulously established compromise. A carefully controlled RT will increase fullness of tone and will help loudness, definition, and diffusion.However,the establishing of an ideal RT alone is no guarantee that a hall will be acoustically excellent for the performance of music; it is a contributing factor only.

3. Acoustical considerations Definition will be satisfactory if the initial time-Delay gap does not exceed 20 msec; if the direct sound is loud enough relative to the reverberant sound, that is, listeners are are reasonably close to the sound source; and if there is no echo. Providing an adequate supply and distribution of bass tones over a large audience area( above 2500 seats) is a serious acoustical problem, in part because the fundamentals of several musical instruments are relatively week and most of the time only their harmonics are heard.

4. Acoustical considerations To achieve uniform quality of sound over the entire seating area balconies should not protrude too deeply into the air space of the room; listeners should have unobstructed sight lines so that they receive ample direct sound, the should be of reasonable size and proportion, and concave enclosures should be avoided.

5. Acoustical considerations Echo will be particularly noticeable if the RT is short and diffusion is inadequate. The longer the RT in a room, the less trouble can be expected from echo. The longer RT will cover up the single intrusions of an echo. In checking echo-producing spots, it should always be borne in mind that the acoustical design of rooms is a three dimensional problem.

6. Acoustical considerations The frequencies of sounds involved in the acoustics of music halls extend over a considerable wide range than those for speech, from about 30 Hz for certain musical instruments to about 12,000 Hz, including those high-frequency components of musical sounds which characterize some musical instruments.

7. Acoustical considerations Particular attention is required to control noises and vibrations originating from the heating, ventilation and air –conditioning system; from nearby spaces; mechanical and electrical rooms; and from surface, underground, and air transportation.

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